Mysql slave invalidating query cache entries
We are looking for community feedback on the use-cases for the Query Cache in My SQL.
As astute followers will notice, the query cache is now off by default in 5.6, but realistically it’s always been disabled because the previous configuration was with zero memory allocated to it.
Scale Arc has introduced auto cache invalidation to the industry – a method for automatically invalidating cache entries that enables true ACID-compliant caching.
For example, consider a product catalog table with a column of “product_id.” The application issues select or update queries to retrieve or update data from the table using “product_id.” Scale Arc uses the “product_id” value as the metadata to tag the cache objects internally.
Each item has a unique identifier that is used to query the data, making it a prime candidate for auto cache invalidation.
Auto cache invalidation can also be useful where point selects are prevalent but cannot be cached using the TTL-based method.
In a situation like this, the query cache can mask performance problems caused by missing indexes, which makes it helpful for novice users.
去slave从库上查看运行状态，果然Seconds_Behind_Master: 28810，而且提示Slave_SQL_Running_State: System lock而且这个是变化的，有的时候提示Slave_SQL_Running_State: invalidating query cache entries (table)，而且Seconds_Behind_Master: 29086 不停的增长着： show slave status\G *************************** 1.